As is well known, one method of transmitting message information is to modulate the amplitude or phase of an electromagnetic carrier with message signal information. In so doing, it is the common practice to hold the orientation of the angle of linear polarization of the carrier constant -- usually, but not necessarily, vertical or horizontal. As is also well known, when the ionosphere is used as the propagation medium for high frequency communication, it's electron content and the presence of the earth's magnetic field cause an undesirable change in the polarization angle of the electromagnetic wave. It has been further noted that the amplitude, frequency or phase characteristics of the wave are similarly affected in the time domain -- with the overall result being a slowly varying fading in received signal strengths. This has been found especially prevalent in satellite communications, and requires critical receiver designs for acceptable system performance.